I actually think Shield Bash is a very good perk – just not quite as very good as many of the other Utility ones.
The Knock Back skill already has a +25% chance to hit (the best odds of any attack) but doesn’t do any damage and is highly fatiguing. With the perk, the absolute fatigue is reduced considerably and the relative fatigue vs the enemy more or less overturned. Also, any hit does damage, not much, but the high hit chance means that it can be done regularly while wearing the enemy down, diminishing their morale, putting them into hazardous positions from where they can be attacked with more lethal weapons etc.
